1. Field of the Invention
The present invention is directed to a high power semiconductor module and, more particularly, to an insert-molded leadframe which optimizes and improves the interface between a power stage and a driver board of the high power module.
2. Description of the Related Art
Conventional power control modules include a power train circuit which comprises two main components--a power stage and a driver board. FIG. 1 schematically illustrates a prior art power stage consisting of power conductors and a component board 2 which operates in conjunction with a module/heat sink assembly 4. The component board 2 includes power components such as diodes, MOSFETs, IGBTS, bipolar transistors, etc. which are connected to form various kinds of circuits such as half bridges, full wave bridges, voltage doublers, and the like.
The power components on component board 2 are controlled by a driver board 6 which contains control circuits such as logic circuitry, microprocessors, and the like to control the power provided from the power elements 2 and 4 to be delivered to a motor or a light ballast, for example.
Another known power control module arrangement is illustrated schematically in FIG. 2, in which driver board 6 interfaces with power components (diodes, MOSFETs, IGBTs) 8 installed on an IMS (insulated metal substrate) board 10. Interconnection between IMS board 10 and driver board 6 is effected through vertical pins 12 that are received in through-holes 14 on the driver board 6. The IMS board 10 is mounted directly to a heat sink 16. The heat sink 16 and IMS board 10 make up the power portion 18 of the module.
IMS substrates such as IMS board 10 are known in the art. Such substrates have semiconductor chips or die thermally secured thereto. The substrate has a relatively thick aluminum body covered by a very thin insulation layer which, in turn, carries a copper pattern that is electrically insulated from the aluminum. Typically, chips are mounted on one or more heat spreaders, to improve thermal management of the heat generated by the chips during operation of the device.
The IMS substrate also includes conductor patterns for receiving bonding wires and effecting connection to the main device terminals. Thus, the die and chips may be internally interconnected to one another on the IMS substrate by stitch-bonding of parallel lead wires. These wires ultimately are connected to pins 12, which extend externally of the casing comprising the power package.
For some time, the industry has been searching intensively for improvements which reduce the cost of circuitry of this type, result in circuits which have a smaller footprint, and deliver improved connectivity between the power circuitry and the driver board.